1. Field of the Invention
The present invention relates to solidified biomass, and more specifically relates to solidified biomass utilizable as an alternative fuel to coal coke and also as material utilizable for a variety of purposes.
The raw biomass material according to the present invention is defined as a refreshable organic resource derived from organism other than fossil fuel. In this specification, maximum compressive strength (MPa) is indicative of hardness based on JISZ2111 ‘Compression Test Method of Wood’
A technique for carbonizing the raw biomass material (complete carbonization) is as follows. The raw biomass material such as wood, bark, bamboo or rice hull is heated within the space in which oxygen does not exist or is supplied under control, and then products are obtained, such as gas (e.g., wood gas), liquid (e.g., acetic acid, tar) or solid (e.g., charcoal). In particular, in this invention, the semi-carbonized solid is obtained by stopping carbonizing the raw biomass material before it is completely carbonized so that the raw biomass material is carbonized without releasing combustible gas or liquid. Because the semi-carbonized solid and pre-semi-carbonized solid are in solid state, their transport efficiency and energy efficiency are increased.
2. Description of the Related Art
Global environment problems has become more and more serious in recent years, and reduction of greenhouse gas emission based on Kyoto Protocol adopted at the 3rd conference of the parties of the United Nations Framework Convention on Climate Change (COP3), securement of primary energy sources, and development of clean and renewable energy sources have been pressingly needed in consideration of predicted depletion of fossil fuel in the future.
Biomass has garnered attention as a breakthrough to overcome the situation at the present days.
However, crude biomass material is high in void fraction, bulky, and very low in transportation efficiency. Further, it is relatively low in calorific value, development of transformational technology to convert it to high-value-added products is demanded.
On the other hand, for rapid iron and steel demand in china in recent years, the cost of the coal coke soars suddenly, and the management of foundry industry and iron and steel manufacturers in our country is remarkably oppressed. This is attributable to the fact that domestic production of coal coke is poor and manufacturers of our country depend more on Chinese-produced coal coke.
In the face of such a circumstance, it is desired earnestly in the field of foundry and iron making to develop solid fuel of high hardness made of biomass that can be substituted for several percentages to several tens of percentages of coal coke, thereby reducing fuel cost and also reducing greenhouse gas emission by virtue of carbon-neutral nature of the biomass.
Further, it is important that the quality of ingot is not degraded in quality by utilizing alternative coke fuel.
As technology for utilizing heat of biomass, there are disclosed pellet processing technology (see patent literature 1 mentioned below, for example) and ogalite processing technology (see patent literature 2 mentioned below, for example) as well as widely known carbonization of biomass.
Pellets and ogalite are pressure-densified fuel made by dewatering by allowing free water contained in wood to evaporate at 100° C., thereby improving transportability and combustibility.
Further, there are disclosed a processing method in which biomass material is cut into narrow chips and carbonized in order to obtain carbide efficiently (see patent literature 3 mentioned below, for example), a processing method for producing solid fuel with high energy yield having high energy density by volume and weight (see patent literature 4 mentioned below, for example), and a processing method for producing half-carbonized and pressure-densified fuel (Bio-Carbonized and Densified Fuel, hereafter referred to as BCDF) of high transportability to further improve transportability (see patent literature 5 mentioned below, for example).
BCDF is solid fuel from which a part of chemically-bonded water contained in cellulose, etc. as well as free water contained in wood are dehydrated, thereby further improving transportability and combustibility.
The patent literatures 1 to 5 aim to produce solid fuel with increased heat energy yield in order to efficiently utilize woody biomass as a heat source.
However, woody biomass group solid fuel produced by methods mentioned above does not have enough calorific value as compared with coal coke and further is not enough in hardness. Therefore, the solid fuel cannot endure the severe condition when burned in the furnace together with coal coke; it is destroyed and burned in the furnace, resulting in that it is difficult for the solid fuel to work as alternative fuel to coal coke.
Further, there are various kinds of biomass such as herb group biomass (grass, sunflower, etc.) and leftover food group biomass (bean-curd refuse, rice hulls, etc.), which are higher in water content and higher in void fraction as compared with wood biomass, so less suitable to utilize as solid fuel, and have been disposed of unutilized. Means to effectively utilize those kinds of biomass has been groped.
Patent literature 1: Japanese Laid-Open Patent Application No. S52-101202
Patent literature 2: Japanese Utility Model Gazette No. H08-8085
Patent literature 3: Japanese Laid-Open Patent Application No. 2004-43517
Patent literature 4: Japanese Laid-Open Patent Application No. 2003-213273
Patent literature 5: Japanese Laid-Open Patent Application No. 2003-206490